1. Field of the Invention
The present invention relates to a hard disk drive, and more particularly, to n apparatus to lock an actuator of a hard disk drive, to prevent a magnetic head from escaping from a parking zone of a disk when the disk is stopped.
2. Description of the Related Art
Hard disk drives (HDDs) are auxiliary memory devices of a computer to read out data stored on a magnetic disk and record data on the magnetic disk using a magnetic head.
FIG. 1 is a plan view illustrating a conventional hard disk drive. FIG. 2 is an exploded perspective view illustrating a conventional actuator and a voice coil motor.
Referring to FIGS. 1 and 2, a conventional hard disk drive includes a magnetic disk (hard disk) 20 which is a recording medium for recording data, a spindle motor 30 installed on a base plate 10, to rotate the disk 20, and an actuator 40 having a magnetic head 41 to record and reproduce data on and from the disk 20.
In the conventional hard disk drive, a plurality of disks are installed to increase a data storage capacity. Recently, one or two disks are sufficient to store data, as a surface recording density of a disk has sharply increased. In particular, a hard disk drive using a single disk, in which data is recorded on only one side of the disk, has been developed. In this case, since only one magnetic head and one arm are needed, a slim hard disk drive is available. Conventionally, a voice coil motor having a magnet provided at each of the upper and lower sides of the coil has been mainly used. However, as shown in the drawings, for the actuator 40 having only one arm 46 for one disk, the voice coil motor 50 of a one-magnet type, in which the magnet 53 is installed at either the upper side or lower side of the coil 56 is mainly used. Since the entire height of the voice coil motor 50 can be reduced, manufacturing a slim hard disk drive is simplified.
Typically, a plurality of the disks 20 are provided and separated by a predetermined distance from each other, and the disks 20 are rotated by the spindle motor 30. A parking zone 21 is provided at an inner circumferential side of the disk 20, in which a slider 42, on which the magnetic head 41 is mounted, is disposed when the power is turned off. A data zone 22 is provided outside the parking zone 21, in which a magnetic signal is recorded.
The actuator 40 pivots around a pivot shaft 47 provided on the base plate 10. The actuator 40 has an arm 46, and a pivot hole 48 is located in the middle of the arm 46 so that the arm 46 is coupled to the pivot shaft 47. A suspension 44, supporting the slider 42 so that the slider 42 is elastically biased toward a surface of the disk 20, is installed at one end portion of the arm 46. A coil 56 of the voice coil motor (VCM) 50 is coupled to an other end portion of the arm 46 by interposing a molding portion 55. The actuator 40 is actuated by the VCM 50.
The VCM 50 includes the coil 56 installed on the arm 46 as described above. A lower yoke 51 is fixedly installed on the base plate 10 with a predetermined interval under the coil 56. An upper yoke 52 is installed above the coil 56, and is coupled to the lower yoke 51 by a screw 59. A magnet 53 is attached to the bottom surface of the upper yoke 52 and is separated a predetermined distance from the coil 56.
In the conventional hard disk drive having the above structure, while data is recorded and reproduced, a lifting force from the rotation of the disk 20 and an elastic force from the suspension 44 are applied to the slider 42. Accordingly, the slider 42 is lifted and maintained at a height where the lifting force and the elastic force are balanced above the data zone 22 of the disk 20. Thus, the magnetic head 41 mounted on the slider 42 maintains a predetermined interval with the disk 20 and records and reproduces data with respect to the disk 20.
When the power is turned off and the disk 20 stops rotating, the lifting force lifting the slider 42 disappears. Consequently, the slider 42 must be moved out of the data zone 22 of the disk 20 in advance, to prevent damage to the data zone 22 caused by the slider 42 contacting the data zone 22. That is, the VCM 50 drives the arm 46 of the actuator 40 to move above the parking zone 21 of the disk 20 before the rotation of the disk 20 is completely stopped, and the slider 42 safely lands in the parking zone 21 even when the disk 20 is completely stopped. Thus, damage to the data zone 22 can be prevented.
When the power is turned on and the disk 20 resumes rotating, the lifting force is generated again and accordingly the slider is lifted. The slider 42 in a lifted state is moved to the data zone 22 of the disk 20 as the arm 46 pivots by the VCM 50. Then, the magnetic head 41 mounted on the slider 42 performs recording and reproduction of data with respect to the data zone 22 of the disk 20.
An actuator locking apparatus 60, to lock and prevent the actuator 40 from pivoting after the slider 42 is accommodated in the parking zone 21 of the disk 20, is provided in the hard disk drive. That is, when the power is turned off, if the hard disk drive is subjected to an external impact, the actuator locking apparatus 60 prevents the actuator 40 from pivoting, and thereby prevents the magnetic head 41 from moving to the data zone 22 from the parking zone 21.
The actuator locking apparatus 60 includes a metal piece 63 installed at the other end portion of the arm 46, a bending portion 66 provided at the upper yoke 52 and having a slot 67 of predetermined width, and a contact portion 64 provided at the lower yoke 51 and contacting a lower surface of the bending portion 66.
The structure and problems of the conventional actuator locking apparatus are described below with reference to the accompanying drawings.
FIG. 3 is a side view of a VCM portion to explain the conventional actuator locking apparatus. FIG. 4 is a perspective view illustrating the conventional actuator locking apparatus. FIG. 5 is a view for explaining the problems of the conventional actuator locking apparatus. Here, the same reference numerals as those shown in FIGS. 1 and 2 indicate the same elements having the same functions.
Referring to FIGS. 3 through 5, the bending portion 66 is bent downward from an edge of the upper yoke 52 of the VCM 50. The contact portion 64, contacting the lower surface of the bending portion 66, protrudes from the edge of the lower yoke 51. The slot 67 of predetermined width is located in the bending portion 66 along a center line C of the arm 46. A coupling protrusion 61 protrudes from the other end portion of the arm 46. A damper 62 is inserted around the coupling protrusion 61, and the metal piece 63 is attached to one side of the damper 62.
The yoke 52 is magnetized by the magnet 53 attached to the bottom surface thereof. Accordingly, a magnetic flux flows from the bending portion 66 of the upper yoke 52 to the contact portion 64 of the lower yoke 51. The magnetic flux leaks around the slot 67 and, due to the leakage of the magnetic flux, the metal piece 63 provided at the arm 46 adheres to the bending portion around the slot 67.
In the above actuator locking apparatus 60, since a magnet is not provided on the upper surface of the lower yoke 51, a distance between the arm 46 and the lower yoke 51 is very narrow. Thus, the height of a lower portion of the bending portion 66 is very short. Since the metal piece 63 provided at the arm 46 accurately adheres to the bending portion 66 around the slot 67 when the center of the metal piece 63 matches the center of the slot 67, the center of the slot 67 must be disposed on the center line C of the arm 46. Thus, it is not possible to arbitrarily set the position of the slot 67 higher than the center line C of the arm 46 to increase the height of the lower portion of the bending portion 66.
Due to the above structural limit of the conventional actuator locking apparatus 60, the lower portion of the bending portion 66, having a low height, can be easily bent during an assembly process of the lower yoke 51 and the upper yoke 52. In particular, the length of the bending portion 66 is typically designed to be slightly greater than the interval between the upper yoke 52 and the lower yoke 51 to improve the contact between the bending portion 66 and the contacting portion 64. In this case, the lower portion of the bending portion 66 can be easily bent. When the lower portion of the bending portion 66 is bent, a contact area between the bending portion 66 and the contact portion 64 decreases, so that a magnetic flux flowing from the bending portion 66 to the contact portion 64 decreases. Accordingly, the leakage of the magnetic flux around the slot 67 decreases. Also, the attachment between metal piece 63 and the bending portion 66 becomes unstable.
To prevent the contact portion 64 from interfering with the metal piece 63 contacting a side surface of the bending portion 66, a side surface of the contact portion 64 towards the metal piece 63 is offset slightly by a distance D1 behind the side surface of the bending portion 66. Accordingly, the entire lower surface of the bending portion 66 does not contact an upper surface of the contact portion 64, and thus, the magnetic flux flowing from the bending portion 66 to the contact portion 64 decreases.
Since the above problems weaken the attaching force between the metal piece 63 and the bending portion 66, the metal piece 63 can be easily detached from the bending portion 66 by a relatively small external impact. Accordingly, the arm 46 of the actuator 40 pivots and the magnetic head contacts the data zone of the disk, possibly damaging the data zone of the disk. Also, since the condition of an attaching force between the metal piece 63 and the bending portion 66 being under an allowed standard is considered as being defective, productivity in manufacturing hard disk drives is lowered.